If I used a wide image instead of a map how would I make it so there would be collisions? If someone could make an example out of this example image it would be nice. Thanks a bunch!
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2D Collisions Help
Blitz3D Forums/Blitz3D Beginners Area/2D Collisions Help Looking at the image, it looks like you intend to use that image for the scene in some sort of platform game. (Please let me know if my assumptions about what you are trying to do is incorrect.)
What I'm thinking is that your character will be moving around on top of the green bits and that he/she will be able to move through the blue bits (the "sky")
If that's correct, what I'd do is this - set the mask colour of your image to the rgb colours of the blue you have there.
You do this like:
image = loadimage()
maskimage image, r, g, b
Then draw your image to the screen. Now this will make the blue bits appear transparent, so just set your clscolor to the r, g, b of the blue you used:
clscolor r, g, b
Then to detect if your character has collided with the green bits of your image, you can just use a simple:
if imagescollide(map, 0, 0, 0, character, charx, chary,charframe)
endif
I hope this helps, but if I've assumed incorrectly, just let us know. I'm sure everyone here would be happy to help.
What I'm thinking is that your character will be moving around on top of the green bits and that he/she will be able to move through the blue bits (the "sky")
If that's correct, what I'd do is this - set the mask colour of your image to the rgb colours of the blue you have there.
You do this like:
image = loadimage()
maskimage image, r, g, b
Then draw your image to the screen. Now this will make the blue bits appear transparent, so just set your clscolor to the r, g, b of the blue you used:
clscolor r, g, b
Then to detect if your character has collided with the green bits of your image, you can just use a simple:
if imagescollide(map, 0, 0, 0, character, charx, chary,charframe)
endif
I hope this helps, but if I've assumed incorrectly, just let us know. I'm sure everyone here would be happy to help.
Looking at the image, it looks like you intend to use that image for the scene in some sort of platform game.
Yes. You are correct. What I'm thinking is that your character will be moving around on top of the green bits and that he/she will be able to move through the blue bits (the "sky")
Again, you are correct. Then to detect if your character has collided with the green bits of your image, you can just use a simple:
if imagescollide(map, 0, 0, 0, character, charx, chary,charframe)
endif
I don't understand what to put between the If and EndIf. What would I put to make it so that the character doesn't go through the green parts? if imagescollide(map, 0, 0, 0, character, charx, chary,charframe)
endif
How come this doesn't work? (no media needed)
Graphics 640,480,32,2 Global backimage=CreateImage(640,480) SetBuffer ImageBuffer(backimage) ClsColor 0,128,255 Cls Color 0,155,0 Rect 0,480-100,640,100,True Rect 100,300,250,35,True MaskImage backimage,0,128,255 Global charimage=CreateImage(50,50) SetBuffer ImageBuffer(charimage) Color 255,0,0 Rect 0,0,50,50,True SetBuffer BackBuffer() ClsColor 0,128,255 Global px#=20 Global py#=320 Global gravity#=4 Global jumping=False While Not KeyHit(1) Cls DrawImage backimage,0,0 DrawImage charimage,px,py If KeyDown(205) px=px+1 EndIf If KeyDown(203) px=px-1 EndIf If px>690 px=-50 EndIf If px<-50 px=690 EndIf If KeyHit(57) If jumping=False jumping=True EndIf EndIf If jumping=True py=py-gravity gravity=gravity-0.08 If ImagesCollide(backimage,0,0,0,charimage,px,py,0) gravity=4 jumping=False EndIf EndIf Flip Wend End
Aha! Well, it's always easier to spot things when we're able to run your program and see exactly where you're getting problems.
Well, first of all, your red block can move through the green parts when it's moving left and right because you haven't yet implemented the collision detection for left and right. All you have to do for this is allow the block to move left and right ONLY IF it wont collide with the wall by moving the 1 unit that you have specified for its movement rate.
I've added this into your code and marked the added lines with "X axis collision detection added"
I've also changed your jumping algorithm slightly. I've changed the way that you've initialised your variables and also changed the way your jumping algorithm actually works. Run the following code and see if you like it:
Edit:
Oh, and by the way, you may notice that your block is now falling off the sides of the map, but that should be easily corrected by making the image wider and having a floor on which it can move outside of the bounds of the screen. I haven't bothered to change this though. Just ask if you need more help.
Well, first of all, your red block can move through the green parts when it's moving left and right because you haven't yet implemented the collision detection for left and right. All you have to do for this is allow the block to move left and right ONLY IF it wont collide with the wall by moving the 1 unit that you have specified for its movement rate.
I've added this into your code and marked the added lines with "X axis collision detection added"
I've also changed your jumping algorithm slightly. I've changed the way that you've initialised your variables and also changed the way your jumping algorithm actually works. Run the following code and see if you like it:
Edit:
Oh, and by the way, you may notice that your block is now falling off the sides of the map, but that should be easily corrected by making the image wider and having a floor on which it can move outside of the bounds of the screen. I haven't bothered to change this though. Just ask if you need more help.
Graphics 640,480,32,2 Global backimage=CreateImage(640,480) SetBuffer ImageBuffer(backimage) ClsColor 0,128,255 Cls Color 0,155,0 Rect 0,480-100,640,100,True Rect 100,300,250,35,True MaskImage backimage,0,128,255 Global charimage=CreateImage(50,50) SetBuffer ImageBuffer(charimage) Color 255,0,0 Rect 0,0,50,50,True SetBuffer BackBuffer() ClsColor 0,128,255 Global px#=20 Global py#=320 Global gravity#=0 ; Changed this from 4 initially Global jumping=True ; Changed this from false initially ; You can now basically regard the variable you called "jumping" as "blockIsInTheAir" While Not KeyHit(1) Cls DrawImage backimage,0,0 DrawImage charimage,px,py If KeyDown(205) ;X axis collision detection added If Not ImagesCollide(backimage,0,0,0,charimage,px+1,py,0) px=px+1 EndIf EndIf If KeyDown(203) ;X axis collision detection added If Not ImagesCollide(backimage,0,0,0,charimage,px-1,py,0) px=px-1 EndIf EndIf If px>690 px=-50 EndIf If px<-50 px=690 EndIf ; I Changed this bit If KeyHit(57) And jumping = False gravity = 4 jumping=True EndIf If ImagesCollide(backimage,0,0,0,charimage,px,py,0) gravity=0 jumping = False Else py=py-Int(gravity) gravity=gravity-0.08 ; The more complicated bit ; Moves the block up so that it is not in contact with the floor ; This prevents the block from getting stuck in the floor after jumping Repeat If ImagesCollide(backimage,0,0,0,charimage,px,py,0) py=py-1 jumping = False gravity = 0 Else Exit EndIf Forever EndIf ; Changes finish here Flip Wend End
Great! Thank you a lot!
EDIT: One thing... :) I moved up the floating green block 50 pixels and when I go underneath it and jump it goes straight to the top of the green block. Could you show me how to make it so that it just cancels out some of the jump and the red block falls back down?
EDIT: One thing... :) I moved up the floating green block 50 pixels and when I go underneath it and jump it goes straight to the top of the green block. Could you show me how to make it so that it just cancels out some of the jump and the red block falls back down?
Sure! I must admit that I forgot about that circumstance!
All you have to do is change the bit that I labelled "The more complicated bit" to this:
Oh, and by the way, I'm sure that this is not the only way to do what you want to do - it's just how I would do it! I'm sure someone else could offer a different approach.
But if it works...
Oh, and if you want more realistic physics, instead of setting gravity to zero with each collision, you could have it "bounce" by doing this:
All you have to do is change the bit that I labelled "The more complicated bit" to this:
; The more complicated bit If gravity < 0 Repeat If ImagesCollide(backimage,0,0,0,charimage,px,py,0) py=py-1 jumping = False gravity = 0 Else Exit EndIf Forever ElseIf gravity > 0 Repeat If ImagesCollide(backimage,0,0,0,charimage,px,py,0) py=py+1 gravity = 0 Else Exit EndIf Forever EndIf
Oh, and by the way, I'm sure that this is not the only way to do what you want to do - it's just how I would do it! I'm sure someone else could offer a different approach.
But if it works...
Oh, and if you want more realistic physics, instead of setting gravity to zero with each collision, you could have it "bounce" by doing this:
If gravity < 0 Repeat If ImagesCollide(backimage,0,0,0,charimage,px,py,0) py=py-1 jumping = False gravity = -gravity / 3 Else Exit EndIf Forever ElseIf gravity > 0 Repeat If ImagesCollide(backimage,0,0,0,charimage,px,py,0) py=py+1 gravity = -gravity / 3 Else Exit EndIf Forever EndIf
Thank you very much.